Break-in compositions for internal combustion engines



fires This invention relates to the running-in of various engines and is particularly directed to an improved method of running-in engines quickly and efficiently, and to compositions therefor.

When engines such as internal combustion engines are first assembled perfect congruence or mating between the piston rings and cylinder bores generally do not exist. Running-in or breaking-in engines is generally essential so as to prevent-excessively high pressures from building up when the piston rings and cylinder bores are not properly mated and thereby scuffing or galling of the piston rings and cylinder bores. Also, if the engine parts are not mated properly more oil is generally exposed to the combustion gases, resulting in greater oil consumption and deposit formation. This problem is fm'ther aggravated by materials of construction which resist wear and the long periods of time which are at present required for running-in engines which results in increase in costs.

Various methods are used for breaking-in engines such as the addition of abrasive forming materials such as iron carbonyl to fuels or mineral oils during the break-in period. The use of known abrasive materials or abrasive forming materials generally is undesirable because of their own tendency to cause damage to contacting metal surfaces and form deposits.

It is an object of this invention to provide an improved method of efiectively running-in engines. Another object is to provide an improved composition for runningin engines. Other objects of the invention will be apparent from the following description of the invention.

It has now been discovered that various engines are quickly and effectively run-in by providing a mineral oil having a viscosity index of at least 30 containing a small amount of oil-soluble chromium compound selected from the group consisting of oil-soluble chromium salt of an alkyl salicylic acid and chromium salt of a diketone and dispersing the compounded oil as a concentrate in a fuel, the chromium compound being present in the mineral oil-fuel mixture in a concentration of from about 0.05 to about grams or more and preferably between 0.1 and 2.5 grams per gallon of fuel, and nmning-in the engine with this chromium compounded oil-fuel mixture under close control, and thereafter draining the oil system and fuel supply of the engine preparatory to refilling and normal running.

The chromium compounds employed in oil-fuel mixtures of this invention are selected from (I) oil-soluble neutral or basic chromium salts of alkyl (straight or branch-chain) salicylic acid and (II) oil-soluble chromium salts of diketones. The chromium salts of (I) are neutral and basic chromium salts of alkyl salicylic acid in which the alkyl group contains from 8 to 30, preferably 14 to 22, carbon atoms. Such compounds are neutral and basic chromium C alkyl, C1244 alkyl and C alkyl salicylates. The chromium compounds of (H) are chromium salts of acetyl acetone, diketones such as propionyl acetone, butyrylacetone, valeryl acetone, acetonyl acetone and their homologues.

The chromium compounds are readily prepared by the double decomposition of the sodium salt of the salicylic acid or ketone with a chromium inorganic salt, e.g., chromium nitrate, in water or aqueous alcohol. 'The vice product can be separated by phase separation, filtration or solvent extraction. To avoid partial hydrolysis of'the chromium organic salt immediately upon double decomposition and before the separation of water, it is desirable to carry out the reaction in the presence of alcohol under distillation conditions, the chromium salt solution being added to an alcohol/water mixture of the sodium compound as the alcohol distills from the mixture, and at such a rate as to replace the distillate.

The mineral oil base is one having a viscosity indexof from about 30 to 60 and a viscosity range of from 10300 SUS at 100 F. derived from paratfinic, naphthenic or mixed base crudes. Mineral oils of this type which are particularly preferred are light distillate lubricating oils having a viscosity of 50l00 SUS at 100 R, such as spindle oil, light neutral oil, white spirits machine oil and the like. suitable viscosity and volatility are synthetic liquid bydrocarbons in the lubricating oil viscosity range.

' The amount of chromium compound-added to the fuel as a concentrate in a suitable oil, e.g., a low viscosity index spindle oil of a viscosity range of 10-300 SUS at 100 F., preferably 50 SUS at 100 F. ranges from 1% to 20% or more. The fuel can be of any type appropriate to the type of engine, such as gasoline, diesel fuel, etc. Fuel additives may be present in the fuels, such as may be found desirable to use in the normal running of an engine and these include anti-knock agents, cetane improvers, anti-oxidants, etc.

The method of breaking-in engines according to the present invention may be employed in internal combustion engines generally, Whether of the spark-ignition or the compression ignition type and whether (in the latter case) the fuel charge is ultimately supplied invaporous form, by spray injection or by solid injection. The invention is likewise applicable to free piston engines, designed not for the direct delivery of power, but as generators of hot gas under pressure to the running, for ex ample, of a turbine unit. Further, the engines to be run-in may be stationary, or they may be mobile, whether as propulsive units or asmobile power supply units or both.

The following examples illustrate the application of the invention and its advantages.

Example I A new car fitted with chromium plated top piston rings was stripped after the first 266 miles. The rings were examined and were found to show tool marks and some patches of light scufiing. One chromium plated ring was replaced and the car was run for miles on 4 gallons of a gasoline fuel to which was added of a pint of a concentrate, in a spindle oil of low viscosity index and of a viscosity of 50 SUS at F., of 1.5% by weight of chromium in the form of a chromium alkyl salicylate, giving a concentration in the fuel of 0.25 gram chromium per gallon. After the run the new ring was found to be 75% bedded and the majority of the scutf marks on the other rings had disappeared. The engine was then drained of oil, flushed and refilled. This engine required no oil during the next 2,000 miles of its service, Whereas it is customary for these engines to use up to eight pints during this period.

Example I] a 3,050,3 9 Patented Aug. 21,1962- Other liquid hydrocarbon lubricants of fuel, the speeds were increased progressively up to the maximum of 70 m.p.h. at 150 miles. A careful check onthe oil consumption showed that it had run-in engine of '80 mm. bore and 82.5 mm. stroke) the effect of chromium alkyl salicylate is demonstrated in that a fuel containing 0.5 gm. Cr/tgallon used for 16' hours caused the chromium-plated top rim; to lose 0.0529 gm. in a comparative test-using iron carb'onyly at a concentration of'4lgms. Fe/gallonxthe loss was' only 0.0079 gm,

. 7 "ExampletlV 1 One pint of mineral oil containing 1% of basic QrC -m alkyl' salicylate, 4% Zn dialkyl dithiophosphate and 6.5% chlorinated parafiin waxwas added to six gal-,

lens of gasoline, and a sufficient amount of this oil-fuel mixture was'used to run-in a" new internal combustion engineat around 60 miles per hour for500 miles. At the end of the test period the oil-fuel mixture was remov d and the-engine was found to be clean and in excellent condition.

"It is not clearly understood how chromium compounded oil-fuel mixtures of the invention function in effective- 1y running-in engines. However it is believed that'the decomposition products of the organic chromiunr salts form products such as oxides and other simple chromium com pounds which are so fine a size as to function not as abrasives but as .gentle polishing agents without causing galling and fouling of engine parts, and which are readily eliminated from'the engine system without causing deposits; On the other hand, compounds such as iron and aluminum compounds such as iron naphthenate, aluminum naphthenate, ferrocene, iron carbonyl cause wear of metal parts, deposit formations and excessive oil consumption. Also, some chromium compoundssuch as chromiumsalts of non-aromatic ,carboxylic acid such as naphthenic-acid, organic acid phosphates and the like are ,ineifective for running-in engines-because they cause r 4 deposit formation and large oil consumption. "Thus, with oil-fuel mixtures of this invention gentle polishing is produced which reduces the unwanted asperites smoothly and rapidly and produces a high polish on the working surfaces of the engine, five or more times as effective as' similar oil-fuel mixtures but containing iron carbonyl, iron naphthenate, iron salicylate, or other types of compounds such as aluminum naphthenate or chromium naphthenate such cause excess deposits.

The invention is of particular advantage in engines employing chromium-plated or otherwise specially hardened piston rings.

,We claim as our invention:'

1. In breaking in internal combustion engines with a mineral oil-fuel mixture in which the mineral oil has a. viscosity index of from about 30 to about and aviscosity of from about 10 to about SUS' at 100 F., the, improvement comprising adding to thefuel the mineral oil as defined above, said oil containing only a;small 7 amount of oil-soluble chromium C alkyl salicylate,-

the chromium C alkyl 'salicylate being in a concentration of from about 0.1 to about 2.5 grams of chromium per gallon of mineral oil-fuel mixture.

2. In breaking in internalrcombustion engines with a mineral oil-fuel mixture, the improvement comprising,

while operating the engine, adding on the basis of about six gallons of gasoline, about one pint of mineral'oil composition consisting essentially of a major amount of V 7 mineral oil having a viscostiy index of from about 30 to about 60? and a viscosity of from about 10 to. about 100 SUS at 100 F; and about 1% basic chromium C1448 alkyl salicylate.

References Cited in the file of this patent a UNITED STATES PATENTS 2,086,775 Lyons et al. July 13, 1 937, 2,364,990 Maiottinu, 'Dec.12,'194 4 2,460,700 Lyons Feb. 1, 1949, 2,789,891 Brandes et al. Apr. 23, 2,902,983 I 'Patberg Sept. 8, 1959 j 1 M FOREIGN ,PATENTS' r 702,832 Great-Britain Jan. .27, 1954 

1. IN BREAKING IN INTERNAL COMBUSTION ENGINES WITH A MINERAL OIL-FUEL MIXTURE IN WHICH TH EMINERAL OIL HAS A VISCOSITY INDEX OF FROM ABOUT 30 TO ABOUT 60 AND A VISCOSITY OF FROM ABOUT 10 TO ABOUT 100 SUS AT 100*F., THE IMPROVEMENT COMPRISING ADDING TO THE FUEL THE MINERAL OIL AS DEFINED ABOVE, SAID OIL CONTAINING ONLY A SMALL AMOUNT OF OIL-SOLUBLE CHROMIUM C8-30 ALKYL SALICYLATE, THE CHROMIUM C8-30 ALKYL SALICYLATE BEING IN A CONCENTRATION OF FROM ABOUT 0.1 TO ABOUT 2.5 GRAMS OF CHROMIUM PER GALLON OF MINERAL OIL-FUEL MIXTURE. 